1. Field of the Invention
This invention relates to silver halide photographic materials having improved granularity and color saturation. In particular, the invention relates to a photographic element containing at least two separate layers of different sensitivity to green light, including a more active pyrazoloazole magenta coupler in the more sensitive layer and a less active pyrazoloazole magenta coupler in the less sensitive layer or layers.
2. Description of Related Art
There is a continuing need in the photographic art to improve and optimize the attributes of the film, such as the image structure of the film. In particular, there is a desire to reduce the amount of "noise," or nonuniformity, in the developed film. The visual sensation produced by such nonuniformity is termed "graininess," while the objective measure of the nonuniformity is termed "granularity." See T. H. James, "The Theory of the Photographic Process," (4th ed 1977), pp. 618-33). Preferably, reduction in the granularity of the developed film should be achieved without adversely affecting other photographic parameters, such as sensitivity to light (speed), latitude, sharpness, interimage effects, curve shape, D-max, and density.
Various approaches to optimizing granularity are known in the art. Such approaches include: coating high concentrations of silver; reducing the size of grains in the film; and decreasing the full development of grains by the use of development inhibitors. The foregoing methods are not always desirable, however, since they require the coating of additional silver in order to obtain the desired curve shape and density. The use of more silver is additionally disadvantageous since it often results in increased light scattering, which degrades the performance of the underlying layers. Moreover, use of excess silver can result in difficulties in the removal (bleaching) of the silver from the developed film.
Smearing couplers have also been used to reduce granularity. This method, however, often undesirably reduces the film sharpness.
Another approach, use of couplers that generate low extinction dyes, involves the use of more silver, with the accompanying disadvantages discussed above.
Another method, involving coating reduced amounts of couplers in the layers of the photographic element in order to "starve" the coupler, generally has a negative impact on D-max, curve shape, color saturation, and silver efficiency.
All of the known methods of reducing granularity typically have an adverse effect on other film properties. Accordingly, there is a need for a film that has reduced granularity and the desired high color saturation without adverse impact on other desired photographic parameters such as latitude, sharpness, inner image effects, and total materials laydown for silver, couplers, and other components.